Importance of Groundwater in Productions and Transport of Methylmercury in Lake Superior Tributaries

Background and Need: Methylmercury accumulation in food chains of streams and lakes presents a health hazard to wildlife and humans. Although production of methylmercury occurs in anoxic zones, little is known about production of methylmercury in groundwaters or the factors that govern its transport and fate.

Objectives: We determined the spatial and temporal patterns in mercury (Hg) and methylmercury concentrations in groundwaters and hyporheic zone waters at two contrasting sites and examined relationships to land cover, biogeochemical conditions, and local hydrology.